Key Research Interests

Extending the age range of luminescence dating of quartz using TT-OSL dating

Timing of the anatomical and behavioural origins of Homo sapiens in Africa and their dispersal ‘Out of Africa’

Constructing high-resolution OSL chronologies for early Homo sapiens in Africa and Neanderthals in Europe to determine the timing of important turning points in their behavioural evolution

Quaternary environmental change and its impact on the evolution and dispersal of early Homo sapiens

Quaternary sea-level change

Development and application of advanced luminescence dating methods

My technical speciality is geochronology, focussing on the development of optically stimulated luminescence dating methods for individual sand-sized grains of quartz. Substantive methodological papers reporting new approaches to OSL dating and their application to archaeological questions have been published. The standardised approach for the analysis of individual grains of quartz that Bert and I developed is now used routinely. I also publish extensively on the interpretation of single-grain OSL data and the application of statistical models to the resulting age distributions. More recently, I have also become interested in the further development and testing of thermally-transferred OSL (TT-OSL) to extend the age range of luminescence dating techniques and have been applying it to Middle Pleistocene coastal deposits along the southern African and Australian coasts. My overall aim is to continue improving these techniques to maximise the accuracy and precision of the resulting archaeological and environmental chronologies.

Jacobs, Z., Wintle, A.G. & Duller, G.A.T. 2006. Evaluation of SAR procedures for De determination using single aliquots of quartz from two archaeological sites in South Africa. Radiation Measurements 41: 520-533.

Left to right: Gold-plated aluminium discs with 100 holes precision-drilled into the surface of the disc. Each hole contains an individual sand-sized mineral grain. Each of the grains are individually stimulated with a green laser centre that steers with mirrors onto the centre of the grain. The Risø TL/OSL readers (right) provide us with the capability to irradiate, preheat, illuminate and measure individual grains in an automated way (photos: Risø National Laboratory).

The origins of modern human behaviour and the dispersal of Homo sapiens out of Africa

Over the last decade, I have been part of the iconoclastic team whose discoveries and research at Blombos Cave, South Africa, have forced a reassessment of when and where Homo sapiens first became modern in their behaviour. I was the leading geochronologist on the team and have continued to lead the dating aspects of all further investigations in southern Africa. In 2007, I co-authored a publication in Nature that made a major contribution to our understanding of the behaviour of early Homo sapiens, reporting evidence that modern humans living 165,000 years ago along the southern Cape coast of South Africa had a far more complex lifestyle than seen anywhere else in the world at that time. This finding was critical in closing the gap between the oldest fossils of Homo sapiens, the earliest genetic evidence for the origins of our species, and the first archaeological traces of modern human behaviour. In 2008, I was lead author of a report in Science that made a further important contribution to the topic of modern human behaviour and dispersal. It described a novel systematic dating approach, combined with statistical modelling, that allowed us to pinpoint, with unprecedented accuracy and precision, the timing of two phases of technological and behavioural innovation across southern Africa. These high-resolution chronologies provided, for the first time, a resolution to the long-standing question of when these two bursts of innovation began and ended, and what may have caused their sudden appearance and abrupt demise. I continue to work on sites in southern Africa to extend the common chronology to industries pre-dating and post-dating the Still Bay and Howieson’s Poort.

Left to right: Finely-shaped bifacial foliate stone points, the fossil directeur of the Still Bay lithic industry in South Africa (photo: C.S. Henshilwood). An engraved ochre slab from Blombos Cave, South Africa, dated to 75 ka (photo: C. S. Henshilwood). Examples of the Howieson’s Poort backed artefacts from South Africa, dated to 60-65 ka. (photo: S. Wurz), and a serrated stone point from Umhlatuzana, South Africa (photo: M. Lombard).

Chronologies for Neanderthal occupation in France and Homo sapiens occupation in Morocco

Our own species, Homo sapiens, is the only species of human left on our planet. This is a relatively recent event, as Neanderthals (Homo neanderthalensis) roamed southern Europe until ~30 thousand years (ka) ago and the ‘Hobbits’ of Flores (Homo floresiensis) persisted until ~12 ka ago. It has been suggested that we are the last remaining human species because, with our advanced social and behavioural abilities, we outcompeted our rivals, who are commonly perceived as ‘cognitively challenged dead-ends’. But whether we differed in our behaviour from Neanderthals (or even Hobbits) is currently hotly debated. Some researchers consider that Neanderthal behaviour embraced the full range of ‘modern’ technology, subsistence and symbolism, whereas others argue that significant differences in behaviour existed between the two species. So the fundamental question remains: did Homo sapiens have superior and more complex behaviour than that of other species — giving us a competitive advantage — or did something else lead to the demise of the Neanderthals? The purpose of this project is to provide a firm chronological foundation to answer this question. I aim to provide a reliable timeframe for investigating the similarities and differences between the behavioural patterns of Neanderthals in France and early Homo sapiens in Morocco and southern Africa at a time when — and in localities where — they are known to have not interacted. This will inform us about when, where and perhaps why significant changes occurred in the behaviour of these two species. The data acquired in France will be compared to the data acquired from Homo sapiens sites in Morocco and in South Africa. I have joined forces with archaeologists working in all three regions to help answer some of these fundamental questions.

Left to right: The main sedimentary profile at Pech de l’Azé IV, a Neanderthal occupation site near Carsac in the southwest of France. Zenobia in front of the Neanderthal statue at the National Museum of Prehistory in Les Eyzies, France. General view of the Les Cottès site near Saint-Pierre-de-Maillé (Vienne), France (photos: N. Jankowski).

Pleistocene environmental change and its impact on early Homo sapiens

A key interest in understanding changes in the behaviour of early modern humans through time is whether or not the variations are linked to changes in climate and environment. Many of the archaeological projects I am involved in examine the archaeological evidence within its environmental context. My colleagues and I demonstrated that during periods of favourable climates in southern Africa, caves and rock shelters are more intensively utilised as home bases, possibly because freshwater and other food resources are readily available. When climates deteriorate, the archaeological visibility diminishes in these sites, which may indicate a more nomadic lifestyle where people move after freshwater and prey. By dating aeolian deposits found within archaeological cave sites and along the coast of South Africa, we have also demonstrated that many of the sites were sealed off by large dune systems, rendering the caves unavailable for human occupation for long periods of time. High resolution climate records are not common in southern Africa, but as part of the research project at Pinnacle Point in South Africa, my colleagues and I now have a continuous isotope record from speleothems, which provides a more localised climatic framework for the period of interest. Previously, we had to rely on the Antarctic ice-core record to interpret our data.

Jacobs, Z., Duller, G.A.T., Wintle, A.G. & Henshilwood, C.S. 2006. Extending the chronology of deposits at Blombos Cave, South Africa, back to 140 ka using optical dating of single and multiple grains of quartz. Journal of Human Evolution 51: 255-273.

Left to right: An example of a speleothem drilled for uranium-series dating and stable isotope analyses from Crevice Cave, South Africa (photo: C.W. Marean). A palaeosol near Blombos Cave, South Africa (photo: Bert Roberts). The main sedimentary profile inside Blombos Cave, showing the very distinctive orange sand layer that separates the underlying Middle Stone Age from the overlying Later Stone Age layers (photo: Bert Roberts).

Research Projects

My research spans many fields in the earth and archaeological sciences, and consequently involves close collaboration with leading Australian and international researchers. The projects mentioned below are all interdisciplinary in nature, with luminescence techniques playing a key role in dating of fossils, artefacts and environmental changes.